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Use infix-to-postfix to parse expressions

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This commit is contained in:
Ole Morud
2024-01-29 14:54:23 +01:00
parent 33d07bea37
commit 2f7fc1f1d9
10 changed files with 345 additions and 185 deletions
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317
src/parser.c
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@@ -1,8 +1,15 @@
/*
* TODO:
* line 312
* */
#include "error.h"
#include "file_stream.h"
#include "tokenizer.h"
#include "printable.h"
#include "common.h"
#include "stack.h"
#include <assert.h>
#include <ctype.h>
@@ -11,6 +18,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <inttypes.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
@@ -18,6 +26,7 @@
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))
/* ======= Grammar Rules =======
statement:
@@ -35,37 +44,51 @@ expr
| FLOAT OPERATOR FLOAT {$$ = binary_op_float($1, $3, $2);};
| INT
| FLOAT
============================= */
enum value_type {
VALUE_INTEGER,
VALUE_OPERATOR,
VALUE_FLOATING,
VALUE_TYPE_COUNT,
};
static const char* value_type_str[VALUE_TYPE_COUNT] = {
[VALUE_INTEGER] = "VALUE_INTEGER",
[VALUE_OPERATOR] = "VALUE_OPERATOR",
[VALUE_FLOATING] = "VALUE_FLOATING",
};
static const int operator_precedence[256] = {
['+'] = 0,
['-'] = 0,
['*'] = 10,
['/'] = 10,
};
typedef struct parser {
Token* cur;
Token* next;
Mfile* m;
} Parser;
} ParserState;
bool parser_advance(Error* err, Parser* p)
void parser_print_position(ParserState* p)
{
Mfile m = *(p->m);
m.pos = 0;
int linecount = 0;
int col = 0;
while (!mfile_eof(&m) && m.pos <= p->m->pos) {
char c = mfile_get(&m);
if (c == '\n') {
linecount++;
col = 0;
} else {
col++;
}
}
fprintf(stderr, "\nLine: %d\nCol: %d\n", linecount, col);
}
bool parser_advance(Error* err, ParserState* p)
{
p->cur = p->next;
//if (p->cur)
// token_print(NULL, p->cur);
mfile_skip(p->m, isspace);
p->next = token_read(err, p->m);
if (!error_empty(err)) {
@@ -85,31 +108,31 @@ typedef struct value {
};
} Value;
static Value* parse_operator(Error* err, Token* t)
static void value_print(FILE* out, Value* v)
{
if (t->type != TOKEN_OPERATOR) {
error_push(err, "%s: unexpected token type: %s", __func__, token_type_str[t->type]);
return NULL;
switch (v->type) {
case VALUE_INTEGER:
fprintf(out, "%" PRId64, v->i64);
break;
case VALUE_FLOATING:
fprintf(out, "%lf", v->f64);
break;
default:
fprintf(out, "(bad value)");
break;
}
Value* v = calloc(1, sizeof *v);
if (!v) {
error_push(err, "%s: failed to allocate value: %s", __func__, strerror(errno));
return NULL;
}
v->type = VALUE_OPERATOR;
strncpy(v->op, t->start, MIN(t->end - t->start, sizeof(v->op)));
return v;
}
static Value* parse_int(Error* err, Token* t)
static Value* parse_int(Error* err, ParserState* p)
{
Token* t = p->cur;
if (t->type != TOKEN_INTEGER) {
error_push(err, "%s: unexpected token type: %s", __func__, token_type_str[t->type]);
error_push(err, "(%s) unexpected token type: %s", __func__, token_type_str[t->type]);
return NULL;
}
Value* v = calloc(1, sizeof *v);
if (!v) {
error_push(err, "%s: failed to allocate value: %s", __func__, strerror(errno));
error_push(err, "(%s) failed to allocate value: %s", __func__, strerror(errno));
return NULL;
}
v->type = VALUE_INTEGER;
@@ -117,14 +140,16 @@ static Value* parse_int(Error* err, Token* t)
errno = 0;
v->i64= strtol(t->start, NULL, 10);
if (errno != 0) {
error_push(err, "%s: failed to parse int: %s", __func__, strerror(errno));
error_push(err, "(%s) failed to parse int: %s", __func__, strerror(errno));
return NULL;
}
parser_advance(err, p);
return v;
}
static Value* parse_floating(Error* err, Token* t)
static Value* parse_floating(Error* err, ParserState* p)
{
Token* t = p->cur;
if (t->type != TOKEN_FLOATING) {
error_push(err, "(%s) unexpected token type: %s", __func__, token_type_str[t->type]);
return NULL;
@@ -142,20 +167,12 @@ static Value* parse_floating(Error* err, Token* t)
error_push(err, "(%s) failed to parse float: %s", __func__, strerror(errno));
return NULL;
}
return v;
}
static Value* parse_number(Error* err, Token* t)
{
switch (t->type) {
case TOKEN_FLOATING:
return parse_floating(err, t);
case TOKEN_INTEGER:
return parse_int(err, t);
default:
error_push(err, "(%s) unexpected token type %s", __func__, token_type_str[t->type]);
parser_advance(err, p);
if (!error_empty(err)) {
error_push(err, "(%s) couldn't advance parser", __func__);
return NULL;
}
return v;
}
static void conv_int_to_float(Error* err, Value* val)
@@ -169,15 +186,17 @@ static void conv_int_to_float(Error* err, Value* val)
val->type = VALUE_FLOATING;
}
static Value* parse_binary_expr(Error* err, Value* lval, Value* rval, Value* op)
static Value* binary_op(Error* err, Value* lval, Value* rval, Token* op)
{
if ((lval->type != VALUE_INTEGER && lval->type != VALUE_FLOATING)
|| (rval->type != VALUE_INTEGER && rval->type != VALUE_FLOATING)
|| op->type != VALUE_OPERATOR)
|| op->type != TOKEN_OPERATOR)
{
error_push(err, "%s: unexpected token types: %s %s %s",
__func__, value_type_str[lval->type],
value_type_str[rval->type], value_type_str[op->type]);
value_type_str[rval->type], token_type_str[op->type]);
fprintf(stderr, "\n####\n");
token_print(err, op);
return NULL;
}
@@ -197,10 +216,10 @@ static Value* parse_binary_expr(Error* err, Value* lval, Value* rval, Value* op)
return NULL;
}
fprintf(stderr, "\ndoing op: %s %c %s", value_type_str[lval->type], op->op[0], value_type_str[rval->type]);
//fprintf(stderr, "\ndoing op: %s %c %s", value_type_str[lval->type], op->start[0], value_type_str[rval->type]);
if (rval->type == VALUE_INTEGER && lval->type == VALUE_INTEGER) {
result->type = VALUE_INTEGER;
switch (op->op[0]) {
switch (op->start[0]) {
case '+':
result->i64 = lval->i64 + rval->i64;
break;
@@ -214,11 +233,11 @@ static Value* parse_binary_expr(Error* err, Value* lval, Value* rval, Value* op)
result->i64 = lval->i64 / rval->i64;
break;
}
printf("\nCALCULATED EXPRESSION %ld %c %ld = %ld\n", lval->i64,
op->op[0], rval->i64, result->i64);
//fprintf(stderr, "\nCALCULATED EXPRESSION %ld %c %ld = %ld\n", lval->i64,
// op->start[0], rval->i64, result->i64);
} else if (rval->type == VALUE_FLOATING && lval->type == VALUE_FLOATING) {
result->type = VALUE_FLOATING;
switch (op->op[0]) {
switch (op->start[0]) {
case '+':
result->f64 = lval->f64 + rval->f64;
break;
@@ -232,90 +251,157 @@ static Value* parse_binary_expr(Error* err, Value* lval, Value* rval, Value* op)
result->f64 = lval->f64 / rval->f64;
break;
}
printf("\nCALCULATED EXPRESSION %lf %c %lf = %lf\n", lval->f64,
op->op[0], rval->f64, result->f64);
//fprintf(stderr, "\nCALCULATED EXPRESSION %lf %c %lf = %lf\n", lval->f64,
// op->start[0], rval->f64, result->f64);
}
return result;
}
static Value* parse_expr(Error* err, Parser* p)
static inline int8_t operator_precedence(Token* op)
{
Value* lval = parse_number(err, p->cur);
if (!error_empty(err) || !lval) {
goto generic_error;
}
// wrapped in a function for now because operators longer than 1 char might
// be implemented
static const int8_t lookup[256] = {
['+'] = -20, ['-'] = -20,
['*'] = -10, ['/'] = -10,
['('] = 128, [')'] = 128
};
return lookup[(size_t)(op->start[0])];
}
if (!error_empty(err)) {
goto generic_error;
} else if (p->next->type != TOKEN_OPERATOR) {
parser_advance(err, p);
if (!error_empty(err)) {
goto syntax_error;
static Value* parse_expr(Error* err, ParserState* p)
{
FixedStack op_stack = STACK_INIT;
FixedStack value_stack = STACK_INIT;
fprintf(stderr, "PRATT START\n");
while (1) {
token_print(NULL, p->cur);
switch (p->cur->type) {
case TOKEN_INTEGER:
stack_push(&value_stack, parse_int(err, p));
if (!error_empty(err))
goto fail;
break;
case TOKEN_FLOATING:
stack_push(&value_stack, parse_floating(err, p));
if (!error_empty(err))
goto fail;
break;
case TOKEN_IDENTIFIER:
fprintf(stderr, "identifiers not implemented yet\n");
exit(FATAL_NOT_IMPLEMENTED);
break;
case TOKEN_PAREN_OPEN:
stack_push(&op_stack, p->cur);
parser_advance(err, p);
if (!error_empty(err))
goto fail;
break;
case TOKEN_PAREN_CLOSE:
while (!stack_empty(&op_stack) && ((Token*)stack_top(&op_stack))->type != TOKEN_PAREN_OPEN) {
Value* rval = stack_pop(&value_stack);
Value* lval = stack_pop(&value_stack);
Token* op = stack_pop(&op_stack);
Value* result = binary_op(err, lval, rval, op);
if (!error_empty(err))
goto fail;
stack_push(&value_stack, result);
}
if (((Token*)stack_top(&op_stack))->type != TOKEN_PAREN_OPEN) {
error_push(err, "%s: mismatched parentheses", __func__);
return NULL;
} else {
stack_pop(&op_stack);
}
parser_advance(err, p);
if (!error_empty(err))
goto fail;
break;
case TOKEN_OPERATOR: {
Token* new_op = p->cur;
if (!stack_empty(&op_stack)) {
while (operator_precedence(new_op) < operator_precedence(stack_top(&op_stack))) {
Value* rval = stack_pop(&value_stack);
Value* lval = stack_pop(&value_stack);
Token* op = stack_pop(&op_stack);
Value* result = binary_op(err, lval, rval, op);
if (!error_empty(err))
goto fail;
stack_push(&value_stack, result);
}
}
parser_advance(err, p);
if (!error_empty(err))
goto fail;
stack_push(&op_stack, new_op);
break;}
default:
goto end;
}
return lval;
}
Value* op = parse_operator(err, p->next);
if (!error_empty(err)) {
goto generic_error;
end:
while (!stack_empty(&value_stack) && !stack_empty(&op_stack)) {
Token* op = stack_pop(&op_stack);
Value* rval = stack_pop(&value_stack);
Value* lval = stack_pop(&value_stack);
Value* result = binary_op(err, lval, rval, op);
if (!error_empty(err))
goto fail;
stack_push(&value_stack, result);
}
parser_advance(err, p);
if (!error_empty(err)) {
goto generic_error;
if (stack_len(&value_stack) != 1 && stack_len(&op_stack) != 0) {
error_push(err, "(%s) bad expression", __func__);
goto fail;
}
parser_advance(err, p);
if (!error_empty(err)) {
goto generic_error;
}
if (!error_empty(err)) {
goto generic_error;
} else if (p->cur->type != TOKEN_INTEGER
&& p->cur->type != TOKEN_FLOATING)
{
goto syntax_error;
}
Value* rval = parse_expr(err, p);
if (!error_empty(err)) {
goto generic_error;
}
Value* result = parse_binary_expr(err, lval, rval, op);
if (!error_empty(err)) {
goto generic_error;
}
return result;
syntax_error:
error_push(err, "%s: syntax error, expected binary expression", __func__);
generic_error:
fprintf(stderr, "PRATT END\n");
return stack_top(&value_stack);
fail:
return NULL;
}
static Value* parser_next(Error* err, Parser* p)
static Value* parser_next(Error* err, ParserState* p)
{
if (p->cur->type == EOF || !error_empty(err)) {
if (p->cur->type == TOKEN_EOF || !error_empty(err)) {
return NULL;
}
Value* result;
switch (p->cur->type) {
case TOKEN_INTEGER:
case TOKEN_FLOATING:
{
result = parse_expr(err, p);
if (!error_empty(err)) {
goto syntax_error;
}
break;
}
default:
syntax_error:
{
error_push(err, "(%s) syntax error: unexpected token %s", __func__, token_type_str[p->cur->type]);
return NULL;
case TOKEN_INTEGER:
case TOKEN_FLOATING:
result = parse_expr(err, p);
if (!error_empty(err) || result == NULL) {
goto syntax_error;
}
fprintf(stderr, "result: ");
value_print(stderr, result);
fprintf(stderr, "\n");
break;
default: syntax_error:
error_push(err, "(%s) syntax error: unexpected token %s (%s)", __func__,
token_type_str[p->cur->type], token_str(p->cur));
return NULL;
}
if (p->cur->type != TOKEN_STATEMENT_END) {
error_push(err, "(%s) expected semicolon", __func__);
return NULL;
}
parser_advance(err, p);
return result;
}
@@ -330,12 +416,6 @@ int main(int argc, char** argv)
return EXIT_FAILURE;
}
// create a protected page for debugging purposes
size_t pagesize = sysconf(_SC_PAGESIZE);
void* protected_page = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
mfile_overflow_slope = protected_page + 0;
mprotect(protected_page, pagesize, PROT_NONE);
Error err = ERROR_INIT;
Mfile* m = mfile_open(&err, argv[1]);
if (!error_empty(&err)) {
@@ -344,7 +424,7 @@ int main(int argc, char** argv)
return EXIT_FAILURE;
}
Parser p = {
ParserState p = {
.cur = NULL,
.next = NULL,
.m = m,
@@ -356,6 +436,7 @@ int main(int argc, char** argv)
parser_next(&err, &p);
if (!error_empty(&err)) {
error_print(&err);
parser_print_position(&p);
return EXIT_FAILURE;
}
}